A compact, power-efficient and accurate SAR ADC for ultralow-power wireless applications: Page 3 of 3

April 08, 2015 // By Jean-Pierre Joosting
At the 2015 International Solid State Circuits Conference, imec and Holst Centre have presented a fast, compact and highly accurate successive approximation ADC (or SAR ADC). Consuming only 46 µW from a 1 V supply, the 13 bit ADC achieves the best power efficiency compared to similar work. The chip’s SNDR (or signal-to noise and distortion ratio) is 64.1 dB. Key in the design is an ultralow-power on-chip background calibration that utilizes a redundancy facilitated error-correction scheme. Since the technique is broadly applicable, it can be used in many new ADC designs for ultralow-power wireless applications.
An ultralow-power 6.4 MS/s 13 bit ADC in 40nm CMOS

By using this innovative design, the researchers at imec and Holst Centre have realized a 6.4 MS/s 13 bit ADC in 40nm CMOS. Thanks to the low-power calibration, this ADC achieves an effective number of bits (or ENOB) of 10.4 bit and a state-of-the-art power-efficiency of 5.5 fJ per conversion step at 6.4 MS/s. Overall, the chip consumes 46 µW from a 1 V supply. The ADC achieves 64.1 dB SNDR (or signal-to noise and distortion ratio). In combination with the ENOB, this gives a good indication of the overall dynamic performance of the ADC. When compared to similar work, our ADC achieves the best power efficiency, while also integrating, on chip, a background calibration technique for comparator offset and DAC mismatch.

Figure ADC results: Performance summary and comparison with state-of-the-art. Click image to enlarge.

What’s in it for industrial partners?

Imec and Holst Centre’s SAR ADC is available for interested parties through IP licensing. For more information, visit www2.imec.be/be_en/research/wireless-communication/ultralow-power-wireless-communic.html.

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